From German utility model No. 79 14 940, a plug-assembly rack of the type mentioned above has been known, wherein each of a plurality of hollow sections includes a 90 degree recess with a longitudinal guide that opens thereto. In order to support the individual shelves on this conventional rack, it is necessary to arrange horizontally between the respective vertical hollow sections at least two hollow sections parallel to each other. For joining the latter to the vertical hollow sections, special functions are required. Consequently, the vertical hollow sections have to be made of several parts, and the horizontal hollow sections constitute optical distractions in the complete rack structure, especially where the shelves have to be of glass, as is rather frequently the case with plug-assembly racks of the type mentioned which are to be used for display and decoration purposes. Further, vertical panels can at best be inserted in grooves open to the recesses of the conventional hollow sections. Since these grooves can naturally be but narrow, the range of thicknesses of the panels used is restricted in a very undesirable way.